Method for fabricating a cylinder-type capacitor utilizing a connected ring structure

ABSTRACT

A method for fabricating a capacitor includes forming an isolation layer over a substrate. The isolation layer forms a plurality of open regions. Storage nodes are formed on surfaces of the open regions. An upper portion of the isolation layer is etched to expose upper outer walls of the storage nodes. A sacrificial layer is formed over the isolation layer to enclose the upper outer walls of the storage nodes. The isolation layer and the sacrificial layer are then removed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority of Korean patent applicationnumber 10-2006-0097312, filed on Oct. 2, 2006, which is incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a method for fabricating asemiconductor device, and more particularly, to a method for fabricatinga cylinder type capacitor.

A memory cell size has continuously decreased as the design rule ofdynamic random access memories (DRAM) also decreases. Accordingly, theheight of a capacitor has continuously increased and the thickness hasbecome smaller in order to maintain a desired charge capacitance. Theheight has increased and the thickness has decreased because the chargecapacitance is proportionate to the surface area of an electrode and thedielectric constant of a dielectric layer, and is inverselyproportionate to the distance between the electrodes, i.e., thethickness of the dielectric layer.

FIGS. 1A and 1B illustrate cross-sectional views of a conventionalmethod for fabricating a capacitor. A line A-A′ represents across-sectional view of a substrate structure having a zigzagarrangement with a small spacing distance. A line B-B′ represents across-sectional view of the substrate structure having a zigzagarrangement with a large spacing distance.

Referring to FIG. 1A, an insulation layer 12 is formed over asemi-finished substrate 11. Stack structures, including storage nodecontact plugs 13 and barrier metals 14, are formed in the insulationlayer 12. An etch stop layer and a sacrificial layer are formed over theinsulation layer 12 including the stack structures. The sacrificiallayer and the etch stop layer are etched to form a patterned sacrificiallayer 16 and a patterned etch stop layer 15 thereby defining openregions. Cylinder type storage nodes 17 are then formed on the surfaceof the open regions. The open regions have a certain aspect ratio. Theaspect ratio is a ratio of a bottom critical dimension ‘W’ to a height‘H’ of the open regions.

Referring to FIG. 1B, a wet dip out process is performed to remove thepatterned sacrificial layer 16. Thus, inner walls and outer walls of thecylinder type storage nodes 17 are exposed. However, as the design rulecontinuously decreases, a distance between cylinder type storage nodeshas also decreased in the cylinder type capacitor formation process.Thus, generation of bridges between neighboring storage nodes isincreased despite the optimization of the wet dip out process.

FIG. 1C illustrates a graph showing the probability of bridge generationaccording to different aspect ratios of storage nodes. For instance,when a ratio between the bottom critical dimension ‘W’ to the height ‘H’of the storage nodes in FIG. 1A is larger than 12, the storage nodes maylean and cause neighboring storage nodes to stick together, therebygenerating bridges.

FIG. 1D illustrates a micrographic view of storage nodes without bridgegeneration. FIG. 1E illustrates a micrographic view of storage nodeswith bridge generation. In FIG. 1D, an aspect ratio is 12, and thestorage nodes are arranged with a uniform spacing distance. In FIG. 1E,an aspect ratio is 17, and the storage nodes lean and stick together.

The value of the aspect ratio causing the leaning may be variableaccording to the property or thickness of the electrode and according todry conditions of the sacrificial layer after performing a wet etchingfor forming the cylinders. The undesirable results shown in FIG. 1Egenerally occur when the aspect ratio is larger than 14 for a titaniumnitride (TiN) electrode.

The leaning may be caused by the surface tension of water existingbetween the storage nodes during a dry process which is performed afterthe wet dip output process. As the DRAM becomes smaller, the height ofthe capacitor may need to be increased accordingly to maintain thesurface area of the capacitor. However, the height of the capacitorgenerally needs to be decreased in order to keep the aspect ratio belowa certain level and reduce the bottom critical dimension increase. Thus,it may be difficult to maintain a sufficient surface area. Accordingly,an effective thickness of the dielectric layer may need to be reduced inorder to maintain a satisfactory capacitance because of an insufficientcapacitor surface area.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to a method forfabricating a capacitor in a semiconductor device, which can reduceleaning of storage nodes during a dry process after a wet dip outprocess is performed.

In accordance with an aspect of the present invention, a method forfabricating a capacitor is provided. An isolation layer is formed over asubstrate. The isolation layer defines a plurality of open regions.Storage nodes are formed on surfaces of the open regions. An upperportion of the isolation layer is etched to expose upper outer walls ofthe storage nodes. A sacrificial layer is formed over the isolationlayer to enclose the upper outer walls of the storage nodes. Theisolation layer and the sacrificial layer are then removed.

In accordance with another aspect of the present invention, a method forfabricating a capacitor is provided. An isolation layer is formed over acell region and a peripheral region of a substrate. The isolation layerdefines a plurality of open regions in the cell region. Storage nodesare formed on surfaces of the open regions. An upper portion of theisolation layer is etched to expose upper outer walls of the storagenodes. A sacrificial pattern is formed on the isolation layer to coverthe cell region. The isolation layer is etched in the peripheral regionto expose side portions of the resultant structure obtained afterforming the sacrificial pattern in the cell region. The isolation layerin the cell region and the sacrificial pattern are then removed.

In accordance with still another aspect of the present invention, amethod for fabricating a capacitor is provided. An isolation layer isformed over a cell region and a peripheral region of a substrate. Theisolation layer defines a plurality of open regions in the cell region.The substrate comprises the cell region and the peripheral region.Storage nodes are formed on surfaces of the open regions. A sacrificialpattern is formed on the isolation layer to cover the cell region. Theisolation layer is etched in the peripheral region to expose sideportions of the resultant structure obtained after forming thesacrificial pattern in the cell region. The isolation layer in the cellregion and the sacrificial pattern are removed.

In accordance with still another aspect of the present invention, amethod for fabricating a capacitor is provided. An isolation layer isformed over a cell region and a peripheral region of a substrate. Theisolation layer defines a plurality of open regions in the cell region.Storage nodes are formed on surfaces of the open regions. An upperportion of the isolation layer is etched to expose upper outer walls ofthe storage nodes. A sacrificial pattern is formed over the isolationlayer. The sacrificial pattern encloses the upper outer walls of thestorage nodes. The isolation layer in the peripheral region is etched toexpose side portions of the resultant structure obtained after formingthe sacrificial pattern. The isolation layer in the cell region and thesacrificial pattern are removed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B illustrate cross-sectional views of a conventionalmethod for fabricating a capacitor.

FIG. 1C illustrates a graph showing probabilities of bridge generationaccording to aspect ratios of conventional storage nodes.

FIG. 1D illustrates a micrographic view of storage nodes without bridgegeneration.

FIG. 1E illustrates a micrographic view of storage nodes with bridgegeneration.

FIGS. 2A to 2H illustrate cross-sectional views of a method forfabricating a cylinder type capacitor according to a first embodiment ofthe present invention.

FIG. 3A illustrates a plan view of a photoresist pattern according tothe first embodiment of the present invention.

FIG. 3B illustrates a plan view of open regions according to the firstembodiment of the present invention.

FIG. 3C illustrates a perspective view showing a result after a partialetching is performed on a mould layer according to the first embodimentof the present invention.

FIG. 3D illustrates a plan view showing a result after performing a dryetch-back process on a sacrificial layer according to the firstembodiment of the present invention.

FIG. 3E illustrates a perspective view showing a result after performinga wet dip out process for oxide according to the first embodiment of thepresent invention.

FIGS. 4A to 4H illustrate cross-sectional views of a method forfabricating a cylinder type capacitor according to a second embodimentof the present invention.

FIGS. 5A to 5H illustrate cross-sectional views of a method forfabricating a cylinder type capacitor according to a third embodiment ofthe present invention.

FIGS. 6A to 6G illustrate cross-sectional views of a method forfabricating a cylinder type capacitor according to a fourth embodimentof the present invention.

FIGS. 7A to 7G illustrate cross-sectional views of a method forfabricating a cylinder type capacitor according to a fifth embodiment ofthe present invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS

The present invention relates to a method for fabricating a capacitor.In accordance with some embodiments of the present invention, thelikelihood of leaning of storage nodes generated during a wet dip outprocess and a dry process, which are essential in forming cylinder typestorage nodes, may be reduced by forming sidewalls on upper outer wallsof the storage nodes. Furthermore, using an amorphous carbon layer mayallow fabrication of the capacitor without deteriorating a productionyield because the amorphous carbon layer may be easily removed through adry ashing process after the cylinder type storage nodes are formed.

FIGS. 2A to 2H illustrate cross-sectional views of a method forfabricating a cylinder type capacitor according to a first embodiment ofthe present invention. A line A-A′ represents a cross-sectional view ofa substrate structure having a zigzag arrangement with a small spacingdistance. A line B-B′ represents a cross-sectional view of the substratestructure having a zigzag arrangement with a large spacing distance.

Referring to FIG. 2A, an insulation layer 22 is formed over asemi-finished substrate 21. Storage node contact holes are formed in theinsulation layer 22, and storage node contact plugs 23 are formed in thestorage node contact holes. Although not illustrated, processes forforming transistors, word lines, and bit lines are generally performedbefore forming the insulation layer 22. The insulation layer 22 mayinclude an undoped silicate glass (USG) layer and may be formed to havea thickness ranging from approximately 1,000 Å to approximately 3,000 Å.A patterned etch stop layer 24 is formed over the insulation layer 22. Apatterned mould layer 25 is formed over the patterned etch stop layer24.

The insulation layer 22 is etched using a storage node contact mask toform the storage node contact holes. A polysilicon layer fills thestorage node contact holes and an etch-back process is performed to formthe storage node contact plugs 23. Although not illustrated, barriermetals may be formed over the storage node contact plugs 23. The barriermetals may include titanium (Ti) or titanium nitride (TiN). An etch stoplayer is formed over the insulation layer 22 and the storage nodecontact plugs 23. The etch stop layer may include a nitride-basedmaterial. For instance, the etch stop layer may include a siliconnitride (Si₃N₄) layer.

A mould layer is formed over the etch stop layer. The mould layer mayinclude an insulation layer. For instance, an oxide-based layer such asa phosphosilicate glass (PSG) layer or a plasma enhanced tetraethylorthosilicate (PETEOS) layer may be formed to a certain thicknesssufficient to maintain a necessary surface area for a desired dielectriccapacitance. The mould layer may be formed in a double-layer structureincluding oxide-based layers. The double-layer structure may be formedsuch that an upper oxide-based layer has a smaller etch rate in a wetetch solution for oxide than a bottom oxide-based layer. For example,PSG may be formed and PETEOS may then be formed over the PSG in thedouble-layer structure.

A photoresist layer is formed over the mould layer. A photo-exposure anddeveloping process is performed on the photoresist layer to form aphotoresist pattern 26. It is important for the photoresist pattern 26to arrange openings in a zigzag pattern. The openings are arranged inthe photoresist pattern 26 where subsequent storage nodes are to beformed. The mould layer is etched using the photoresist pattern 26 as anetch barrier to form the patterned mould layer 25 and to form aplurality of open regions 27. The etch stop layer exposed by the openregions 27 are etched to form the patterned etch stop layer 24 and toexpose upper surfaces of the storage node contact plugs 23.

The open regions 27 are formed to have a trench shape. The open regions27 are also referred to as storage node holes because the subsequentstorage nodes are formed on the surface of the open regions 27. The openregions 27 are arranged in a zigzag pattern, mirroring the zigzagarrangement of the photoresist pattern 26. A stack structure, includingthe patterned etch stop layer 24 and the patterned mould layer 25providing the open regions 27, is referred to as an isolation layer 100.The photoresist pattern 26 is then removed.

Referring to FIG. 2B, a conductive layer 28 for forming the storagenodes is formed over the isolation layer 100 and the open regions 27.The conductive layer 28 includes a metal electrode such as TiN orruthenium (Ru). The conductive layer 28 may also include other materialsbesides TiN and Ru. The conductive layer 28 may be formed to have athickness ranging from approximately 200 Å to approximately 400 Å usinga chemical vapor deposition (CVD) method or an atomic layer deposition(ALD) method.

When forming the conductive layer 28 including TiN using the CVD method,a CVD TiN deposition method is performed using titanium tetrachloride(TiCl₄) as a source and using ammonia (NH₃) as a reaction gas at atemperature ranging from approximately 400° C. to approximately 700° C.When forming the conductive layer 28 including Ru, the ALD method or theCVD method is performed using Ru(EtCp)₂ as a source and using oxygen(O₂) gas as a reaction gas at a temperature ranging from approximately200° C. to approximately 400° C. The conductive layer 28 for forming thestorage nodes may include platinum (Pt) formed by the ALD method oriridium (Ir) formed by the ALD method.

Referring to FIG. 2C, a storage node isolation process is performed. Thestorage node isolation process includes performing a dry etch-backprocess on the conductive layer 28. The storage node isolation processmay include performing a CMP process or a dry etch-back process using aphotoresist layer barrier or an oxide-based layer barrier when theconductive layer 28 includes TiN. Using the photoresist layer barrier orthe oxide-based layer barrier may reduce contamination in the openregions 27 during the storage node isolation process.

The storage node isolation process is performed until top surfaces ofthe patterned mould layer 25 are exposed. Thus, cylinder type storagenodes 28A are formed on the surface of the open regions 27, isolatedfrom each other. In other words, the CMP process or the dry etch-backprocess is performed to remove portions of the conductive layer 28formed outside the open regions 27, thereby forming the cylinder typestorage nodes 28A over bottom surfaces and sidewalls of the open regions27.

Referring to FIG. 2D, the patterned mould layer 25 is partially etchedto form a remaining mould layer 25A. Thus, upper outer walls 28B of thestorage nodes 28A are exposed. A remaining isolation layer 101 includesthe remaining mould layer 25A and the patterned etch stop layer 24.

The patterned mould layer 25 is selectively etched using an oxideetchant because the patterned mould layer 25 includes an oxide-basedmaterial. For instance, a wet etch may be used. The wet etch may includeperforming a wet dip out process. The wet etch of the patterned mouldlayer 25 may include etching the patterned mould layer 25 to a thicknessranging from approximately 200 nm to approximately 1,000 nm using abuffered oxide etchant (BOE) or a hydrogen fluoride (HF) solution. Forinstance, approximately 700 nm to approximately 800 nm of the patternedmould layer 25 may be etched.

Referring to FIG. 2E, a sacrificial layer 29 is formed over the storagenodes 28A and the remaining isolation layer 101. The sacrificial layer29 may include a material which may not be etched or which has asubstantially slow etch rate in a wet etch solution for oxide during asubsequent wet dip out process of the remaining mould layer 25A. Forinstance, the sacrificial layer 29 may include an amorphous carbonlayer.

The amorphous carbon layer may be formed using a plasma-based depositionmethod, such as a plasma enhanced chemical vapor deposition (PECVD)method or a plasma enhanced atomic layer deposition (PEALD) method. Theamorphous carbon layer is not easily etched by wet etch solutions foroxide, such as a BOE or a HF solution. The amorphous carbon layer iseasily removed by a dry ashing process in an oxidation ambienceincluding O₂ or ozone (O₃). The amorphous carbon layer used as thesacrificial layer 29 is formed at a temperature ranging fromapproximately 200° C. to approximately 500° C. It is also important tocontrol a thickness of the amorphous carbon layer.

The thickness of the sacrificial layer 29 is controlled such that thesacrificial layer 29 fills a space between neighboring storage nodes 28Ain the A-A′ line direction. The spacing distance between the storagenodes 28A is smaller than of the spacing distance in the B-B′ linedirection (refer to reference denotation 29A). The sacrificial layer 29is formed such that the sacrificial layer 29 partially fills a spacebetween neighboring storage nodes 28A in the B-B′ line direction. Thespacing distance between the storage nodes 28A in the B-B′ linedirection is larger than of the spacing distance between storage nodes28A in the A-A′ line direction (refer to reference denotation 29B). Inother words, the sacrificial layer 29 is formed to have a substantiallyuniform thickness over upper surfaces of the substrate structureincluding the storage nodes 28A in the B-B′ line direction. Thesacrificial layer 29 is formed to have different thicknesses overdifferent parts of the substrate structure because the storage nodes 28Aare formed in a zigzag pattern. In other words, the differentthicknesses of the sacrificial layer 29 results because the spacingdistance between neighboring storage nodes 28A is small in the A-A′ linedirection, and the spacing distance between neighboring storage nodes28A is large in the B-B′ line direction. It is possible to control thethickness of the sacrificial layer 29 because the sacrificial layer 29is formed using a plasma-based deposition method. Controlling thethickness of the sacrificial layer 29 refers to controlling a stepcoverage characteristic.

Referring to FIG. 2F, a dry etch-back process is performed on thesacrificial layer 29 to form first remaining sacrificial layers 29C,second remaining sacrificial layers 29D, and third remaining sacrificiallayers 29E. The dry etch-back process includes performing a plasmaetching using oxygen or ozone when the sacrificial layer 29 includesamorphous carbon.

The first remaining sacrificial layers 29C remain over the storage nodes28A in both directions of the A-A′ line and the B-B′ line after the dryetch-back process of the sacrificial layer 29 is performed. The secondremaining sacrificial layers 29D remain between neighboring storagenodes 28A in the A-A′ line direction, covering a portion of theremaining mould layer 25A between neighboring storage nodes 28A. Thethird remaining sacrificial layers 29E remain between neighboringstorage nodes 28A in the B-B′ line direction such that the thirdremaining sacrificial layers 29E do not fill a space between neighboringstorage nodes 28A. Since the thickness of portions of the sacrificiallayer 29 in the B-B′ line direction is relatively smaller than thethickness of portions of the sacrificial layer 29 in the A-A′ linedirection, portions of the remaining mould layer 25A between the storagenodes 28A in the B-B′ line direction are exposed after the dry etch-backprocess is performed. Thus, the third remaining sacrificial layers 29Eremain on the upper outer walls of the storage nodes 28A.

The dry etch-back process may be performed on the sacrificial layer 29until top corners of the storage nodes 28A are exposed in bothdirections of the lines A-A′ and B-B′. After performing the dryetch-back process on the sacrificial layer 29, the remaining mould layer25A may not be exposed in the A-A′ line direction because of the secondremaining sacrificial layers 29D. The remaining mould layer 25A isexposed in the B-B′ line direction by the third remaining sacrificiallayers 29E.

Thus, the upper outer walls of the storage nodes 28A are enclosed by thethird remaining sacrificial layers 29E in the B-B′ line direction afterthe dry etch-back process. The upper outer walls of the storage nodes28A in the A-A′ line direction are supported by the second remainingsacrificial layer 29D formed between the storage nodes 28A. The thirdremaining sacrificial layers 29E remaining in a spacer formed in theB-B′ line direction are formed as ring type sidewalls enclosing theupper outer walls of the storage nodes 28A. The third remainingsacrificial layers 29E also remain on an upper outer wall of eachstorage node 28A in the A-A′ line direction.

Referring to FIG. 2G, a wet etch process for oxide and a dry process areperformed. For instance, the wet etch process may include performing awet dip out process. During the wet dip out process, the remaining mouldlayer 25A including oxide is removed in both directions of the A-A′ lineand the B-B′ line. The cylinder type storage nodes 28A supported by thering type third remaining sacrificial layers 29E do not lean during thewet dip out process and the dry process.

Referring to FIG. 2H, the first, second, and third remaining sacrificiallayers 29C, 29D, and 29E are removed. The first, second, and thirdremaining sacrificial layers 29C, 29D, and 29E are removed by employinga dry ashing process because the first, second, and third remainingsacrificial layers 29C, 29D, and 29E include amorphous carbon. Amorphouscarbon layers may be removed by dry ashing using oxygen or ozone. Thestorage nodes 28A are not damaged during the dry ashing process becausethe dry ashing process is performed at a low ashing temperature usingoxygen.

Although not illustrated, subsequent dielectric layer and upperelectrode formation processes are performed to form a cylinder typecapacitor. The dielectric layer may include tantalum oxide (Ta₂O₅),aluminum oxide (Al₂O₃), titanium oxide (TiO₂), hafnium oxide (HfO₂),zirconium dioxide (ZrO₂), strontium titanate (STO), barium strontiumtitanate (BST), or a combination thereof. The upper electrode mayinclude a TiN layer formed using a CVD method, a TiN layer formed usingan ALD method, a Ru layer formed using a CVD method, a Ru layer formedusing an ALD method, a Pt layer formed using an ALD method, an Ir layerformed using an ALD method, or a combination thereof.

FIG. 3A illustrates a plan view of a photoresist pattern according tothe first embodiment of the present invention. FIG. 3B illustrates aplan view of open regions according to the first embodiment. FIG. 3Cillustrates a plan view showing a result after a partial etching isperformed on a mould layer according to the first embodiment. FIG. 3Dillustrates a plan view showing a result after performing a dryetch-back process on a sacrificial layer according to the firstembodiment. FIG. 3E illustrates a perspective view showing a resultafter performing a wet dip out process for oxide according to the firstembodiment.

FIG. 3A illustrates a plan view of the open regions 27 according to thefirst embodiment. Diameters D1 and D2 of the open regions 27 arranged ina zigzag pattern are substantially the same in directions of the A-A′line and the B-B′ line, i.e., D1=D2 (also refer to FIG. 2A). A secondspacing distance S2 between the open regions 27 along the B-B′ linedirection is larger than a first spacing distance S1 between the openregions 27 along the A-A′ line direction (also refer to FIG. 2A).

FIG. 3B illustrates a plan view of the resultant substrate structureafter the storage node isolation process is performed. The storage nodes28A are formed on the surface of the open regions 27 of the isolationlayer 100. The storage nodes 28A are formed in a zigzag pattern.

FIG. 3C illustrates a perspective view of the result after the patternedmould layer 25 is partially etched. The remaining isolation layer 101,including the stack structure of the patterned etch stop layer 24 andthe remaining mould layer 25A, remains between adjacent storage nodes28A. The upper outer walls 28B of the storage nodes 28A are exposedbecause portions of the patterned mould layer 25 are etched.

FIG. 3D illustrates a plan view of the resultant substrate structureafter the dry etch-back process is performed on the sacrificial layer 29according to the first embodiment. The second remaining sacrificiallayers 29D remain in a coupling structure in the A-A′ line direction andthe third remaining sacrificial layers 29E remain in a discontinuingstructure in the B-B′ line direction because the dry etch-back processperformed on the sacrificial layer 29 includes performing a blanketetch-back process. The third remaining sacrificial layers 29E enclosingthe upper outer walls of the storage nodes 28A are coupled to each otherby the second remaining sacrificial layers 29D in the A-A′ linedirection. However, the third remaining sacrificial layers 29E are notcoupled to each other in the B-B′ line direction. The first remainingsacrificial layers 29C remain over the storage nodes 28A.

Each upper outer wall of the storage nodes 28A is enclosed by the thirdremaining sacrificial layer 29E. The ring type third remainingsacrificial layers 29E are coupled by the second remaining sacrificiallayers 29D, thereby supporting the storage nodes 28A. Thus, the secondand third remaining sacrificial layers 29D and 29E may be referred to asa connected ring structure fixed around the upper outer walls of thestorage nodes 28A.

FIG. 3E illustrates a perspective view showing the result afterperforming the wet dip out process for oxide according to the firstembodiment. The storage nodes 28A do not lean during the wet dip outprocess and the dry process because the storage nodes 28A are supportedby the second and third remaining sacrificial layers 29D and 29E of theconnected ring structure. The wet dip out process may use a BOE or a HFsolution as an oxide etchant. The wet dip out process is performed for aperiod of time sufficient to remove the remaining mould layer 25A. Thedry process is then performed. The oxide etchant does not penetrate intothe storage nodes 28A during the wet dip out process because the firstremaining sacrificial layers 29C remain over the storage nodes 28A.

According to the first embodiment, the ring type structures are formedaround the upper outer walls of each storage node and are coupled toeach other to form the connected ring structure. The connected ringstructure reduces the likelihood that the storage nodes will lean duringthe wet dip out process for oxide and the dry process, therebydecreasing the likelihood of bridge generation between neighboringstorage nodes. In other words, the connected ring structure decreasesthe likelihood of bridge generation during the wet dip out process andthe dry process which are generally used in forming the cylinder typestorage nodes. Thus, a height of the storage nodes may be maximized tomaintain a sufficient level of capacitance.

FIGS. 4A to 4H illustrate cross-sectional views of a method forfabricating a cylinder type capacitor according to a second embodimentof the present invention.

Referring to FIG. 4A, an insulation layer 32 is formed over asemi-finished substrate 31. The substrate 31 is divided into a cellregion and peripheral regions. Storage node contact holes are formed inthe insulation layer 32, and storage node contact plugs 33 are formed inthe storage node contact holes. Although not illustrated, processes forforming transistors, word lines, and bit lines are generally performedbefore forming the insulation layer 32. The insulation layer 32 mayinclude an undoped silicate glass (USG) layer and may be formed to havea thickness ranging from approximately 1,000 Å to approximately 3,000 Å.A patterned etch stop layer 34 is formed over the insulation layer 32. Apatterned mould layer 35 is formed over the patterned etch stop layer34.

The insulation layer 32 is etched using a storage node contact mask toform the storage node contact holes. A polysilicon layer fills thestorage node contact holes and an etch-back process is performed to formthe storage node contact plugs 33. Although not illustrated, barriermetals may be formed over the storage node contact plugs 33. The barriermetals may include titanium (Ti) or titanium nitride (TiN). An etch stoplayer is formed over the insulation layer 32 and the storage nodecontact plugs 33. The etch stop layer may include a nitride-basedmaterial. For instance, the etch stop layer may include a siliconnitride (Si₃N₄) layer.

A mould layer is formed over the etch stop layer. The mould layer mayinclude an insulation layer. For instance, an oxide-based layer such asa phosphosilicate glass (PSG) layer or a plasma enhanced tetraethylorthosilicate (PETEOS) layer may be formed to a certain thicknesssufficient to maintain a necessary surface area for a desired dielectriccapacitance. The mould layer may be formed in a double-layer structureincluding oxide-based layers. The double-layer structure may be formedsuch that an upper oxide-based layer has a smaller etch rate in a wetetch solution for oxide than a bottom oxide-based layer. For example,PSG may be formed and PETEOS may then be formed over the PSG in thedouble-layer structure.

A first photoresist layer is formed over the mould layer. Aphoto-exposure and developing process is performed on the firstphotoresist layer to form a first photoresist pattern 36. It isimportant for the first photoresist pattern 36 to form openings in azigzag pattern. The openings are formed in the first photoresist pattern36 where subsequent storage nodes are to be formed. The mould layer isetched using the first photoresist pattern 36 as an etch barrier to formthe patterned mould layer 35 and to form a plurality of open regions 37.The etch stop layer exposed by the open regions 37 is etched to form thepatterned etch stop layer 34 and to expose upper surfaces of the storagenode contact plugs 33.

The open regions 37 are formed to have a trench shape. The open regions37 are also referred to as storage node holes because the subsequentstorage nodes are formed on the surface of the open regions 37. The openregions 37 are formed in a zigzag pattern, mirroring the zigzagarrangement of the first photoresist pattern 36. The open regions 37 areformed in the zigzag pattern in substantially the same manner as theopen regions 27 of the first embodiment shown in FIG. 3A. The openregions 37 are formed only in the cell region. A stack structure,including the patterned etch stop layer 34 and the patterned mould layer35 providing the open regions 37, is referred to as an isolation layer200.

Referring to FIG. 4B, the first photoresist pattern 36 is removed. Aconductive layer 38 for forming the storage nodes is formed over theisolation layer 200 and the open regions 37. The conductive layer 38 mayinclude a metal electrode such as TiN or ruthenium (Ru). The conductivelayer 38 may also include other materials besides TiN and Ru. Theconductive layer 38 may be formed to have a thickness ranging fromapproximately 200 Å to approximately 400 Å using a chemical vapordeposition (CVD) method or an atomic layer deposition (ALD) method.

When forming the conductive layer 38 including TiN using the CVD method,a CVD TiN deposition method is performed using titanium tetrachloride(TiCl₄) as a source and using ammonia (NH₃) as a reaction gas at atemperature ranging from approximately 400° C. to approximately 700° C.When forming the conductive layer 38 including Ru, the ALD method or theCVD method is performed using Ru(EtCp)₂ as a source and using oxygen(O₂) gas as a reaction gas at a temperature ranging from approximately200° C. to approximately 400° C. The conductive layer 38 for forming thestorage nodes may include platinum (Pt) formed by the ALD method oriridium (Ir) formed by the ALD method.

Referring to FIG. 4C, a storage node isolation process is performed. Thestorage node isolation process includes performing a dry etch-backprocess on the conductive layer 38. The storage node isolation processmay include performing a CMP process or a dry etch-back process using aphotoresist layer barrier or an oxide-based layer barrier when theconductive layer 38 includes TiN. Using the photoresist layer barrier orthe oxide-based layer barrier may reduce contamination in the openregions 37 during the storage node isolation process.

The storage node isolation process is performed until top surfaces ofthe patterned mould layer 35 are exposed. Thus, cylinder type storagenodes 38A are formed on the surface of the open regions 37, isolatedfrom each other. In other words, the CMP process or the dry etch-backprocess is performed to remove portions of the conductive layer 38formed outside the open regions 37, thereby forming the cylinder typestorage nodes 38A over bottom surfaces and sidewalls of the open regions37. After the storage node isolation process is performed, the storagenodes 38A are formed on the surface of the open regions 37 of theisolation layer 200. The storage nodes 38A are disposed in a zigzagpattern in substantially the same manner as the storage nodes 28A of thefirst embodiment shown in FIG. 3B.

Referring to FIG. 4D, the patterned mould layer 35 is partially etchedto form a remaining mould layer 35A. Thus, upper outer walls 38B of thestorage nodes 38A are exposed. A remaining isolation layer 201 includesthe remaining mould layer 35A and the patterned etch stop layer 34.

The patterned mould layer 35 is selectively etched using an oxideetchant because the patterned mould layer 35 includes an oxide-basedmaterial. For instance, a wet etch may be used. The wet etch may includeperforming a wet dip out process. The wet etch of the patterned mouldlayer 35 may include etching the patterned mould layer 35 to a thicknessranging from approximately 200 nm to approximately 1,000 nm using abuffered oxide etchant (BOE) or a hydrogen fluoride (HF) solution. Forinstance, approximately 700 nm to approximately 800 nm of the patternedmould layer 35 may be etched.

After the patterned mould layer 35 is partially etched, the remainingisolation layer 201, including the stack structure of the patterned etchstop layer 34 and the remaining mould layer 35A, remains betweenadjacent storage nodes 38A. The upper outer walls 38B of the storagenodes 38A are exposed because portions of the patterned mould layer 35are etched.

Referring to FIG. 4E, a sacrificial layer 39 is formed over the storagenodes 38A and the remaining isolation layer 201. The sacrificial layer39 may include a material which may not be etched or which has asubstantially slow etch rate in a wet etch solution for oxide during asubsequent wet dip out process of the remaining mould layer 35A. Forinstance, the sacrificial layer 39 may include an amorphous carbonlayer.

The amorphous carbon layer may be formed using a plasma-based depositionmethod, such as a plasma enhanced chemical vapor deposition (PECVD)method or a plasma enhanced atomic layer deposition (PEALD) method. Theamorphous carbon layer is not easily etched by wet etch solutions foroxide, such as a BOE or a HF solution. The amorphous carbon layer iseasily removed by a dry ashing process in an oxidation ambienceincluding O₂ or ozone (O₃). The amorphous carbon layer used as thesacrificial layer 39 is formed at a temperature ranging fromapproximately 200° C. to approximately 500° C.

The sacrificial layer 39 is formed to have a certain thicknesssufficient to fill a space between neighboring storage nodes 38A. Thesacrificial layer 39 may be formed to cover the substrate structurewithout controlling the thickness of the sacrificial layer 39 because adry etch-back process of the sacrificial layer 39 is omitted in thesecond embodiment, unlike the first embodiment.

Referring to FIG. 4F, a second photoresist layer is formed over thesacrificial layer 39. A photo-exposure and developing process isperformed on the second photoresist layer to form a second photoresistpattern 40. The second photoresist pattern 40 covers the cell region butexposes the peripheral regions of the substrate structure.

The sacrificial layer 39 is etched using the second photoresist pattern40 as an etch barrier. Thus, a sacrificial pattern 39A is formed. Thesacrificial pattern 39A remains only in the cell region because portionsof the sacrificial layer 39 in the peripheral regions are etched. Theremaining mould layer 35A is etched after the sacrificial pattern 39A isformed, thereby forming a mould pattern 35B. The etching of theremaining mould layer 35A may include performing a dry etch process.Portions of the remaining mould layer 35A in the peripheral regions areetched. Thus, the mould pattern 35B defines spaces around the cellregion into which a wet etch solution may flow. The mould pattern 35Bmay be formed such that the mould pattern 35B remains only in the cellregion after the portions of the remaining mould layer 35A are etched inthe peripheral regions. Alternatively, the mould pattern 35B may beformed such that portions of the remaining mould layer 35A remain overthe patterned etch stop layer 34 at a certain thickness in theperipheral regions. An isolation pattern 211 includes the mould pattern35B and the patterned etch stop layer 34.

Referring to FIG. 4G, a wet etch process for oxide is performed. Forinstance, the wet etch process may include performing a wet dip outprocess. The mould pattern 35B including an oxide-based material isremoved during the wet dip out process. A wet etch solution flowssideways into the spaces defined around the cell region and removes themould pattern 35B. Thus, empty spaces 202 are formed between the storagenodes 38A. The sacrificial pattern 39A is not easily etched during a wetdip out process for oxide. Thus, the sacrificial pattern 39A decreasesthe likelihood of leaning storage nodes 38A. The wet dip out process mayuse a BOE or a HF solution as an oxide etchant. The wet dip out processis performed for a period of time sufficient to remove the mould pattern35B. Neighboring storage nodes 38A are supported by the sacrificialpattern 39A during the wet dip out process, and thus, the likelihood ofleaning storage nodes 38A is reduced during a dry process which isperformed after the wet dip out process.

Referring to FIG. 4H, a photoresist ashing process is performed. Thephotoresist ashing process includes a dry ashing process. The secondphotoresist pattern 40 and the sacrificial pattern 39A aresimultaneously removed using the dry ashing process. The sacrificialpattern 39A including amorphous carbon may be removed at substantiallythe same time as the second photoresist pattern 40 because amorphouscarbon can be removed by a dry ashing using oxygen or ozone. The storagenodes 38A are not damaged because the dry ashing process is performed ata low temperature using oxygen.

Although not illustrated, subsequent dielectric layer and upperelectrode formation processes are performed to form a cylinder typecapacitor. The dielectric layer may include tantalum oxide (Ta₂O₅),aluminum oxide (Al₂O₃), titanium oxide (TiO₂), hafnium oxide (HfO₂),zirconium dioxide (ZrO₂), strontium titanate (STO), barium strontiumtitanate (BST), or a combination thereof. The upper electrode mayinclude a TiN layer formed using a CVD method, a TiN layer formed usingan ALD method, a Ru layer formed using a CVD method, a Ru layer formedusing an ALD method, a Pt layer formed using an ALD method, an Ir layerformed using an ALD method, or a combination thereof.

FIGS. 5A to 5H illustrate cross-sectional views of a method forfabricating a cylinder type capacitor according to a third embodiment ofthe present invention.

Referring to FIG. 5A, an insulation layer 42 is formed over asemi-finished substrate 41. The substrate 41 is divided into a cellregion and peripheral regions. Storage node contact holes are formed inthe insulation layer 42, and storage node contact plugs 43 are formed inthe storage node contact holes. Although not illustrated, processes forforming transistors, word lines, and bit lines are generally performedbefore forming the insulation layer 42. The insulation layer 42 mayinclude an undoped silicate glass (USG) layer and may be formed to havea thickness ranging from approximately 1,000 Å to approximately 3,000 Å.A patterned etch stop layer 44 is formed over the insulation layer 42. Apatterned mould layer 45 is formed over the patterned etch stop layer44.

The insulation layer 42 is etched using a storage node contact mask toform the storage node contact holes. A polysilicon layer fills thestorage node contact holes and an etch-back process is performed to formthe storage node contact plugs 43. Although not illustrated, barriermetals may be formed over the storage node contact plugs 43. The barriermetals may include titanium (Ti) or titanium nitride (TiN). An etch stoplayer is formed over the insulation layer 42 and the storage nodecontact plugs 43. The etch stop layer may include a nitride-basedmaterial. For instance, the etch stop layer may include a siliconnitride (Si₃N₄) layer.

A mould layer is formed over the etch stop layer. The mould layer mayinclude an insulation layer. For instance, an oxide-based layer such asa phosphosilicate glass (PSG) layer or a plasma enhanced tetraethylorthosilicate (PETEOS) layer may be formed to a certain thicknesssufficient to maintain a necessary surface area for a desired dielectriccapacitance. The mould layer may be formed in a double-layer structureincluding oxide-based layers. The double-layer structure may be formedsuch that an upper oxide-based layer has a smaller etch rate in a wetetch solution for oxide than a bottom oxide-based layer. For example,PSG may be formed and PETEOS may be then formed over the PSG in thedouble-layer structure.

A photoresist layer is formed over the mould layer. A photo-exposure anddeveloping process is performed on the photoresist layer to form aphotoresist pattern 46. It is important for the photoresist pattern 46to form openings in a zigzag pattern. The openings are formed in thephotoresist pattern 46 where subsequent storage nodes are to be formed.The mould layer is etched using the photoresist pattern 46 as an etchbarrier to form the patterned mould layer 45 and to form a plurality ofopen regions 47. The etch stop layer exposed by the open regions 47 isetched to form the patterned etch stop layer 44 and to expose uppersurfaces of the storage node contact plugs 43.

The open regions 47 are formed to have a trench shape. The open regions47 are also referred to as storage node holes because the subsequentstorage nodes are formed on the surface of the open regions 47. The openregions 47 are formed in a zigzag pattern, mirroring the zigzagarrangement of the photoresist pattern 46. The open regions 47 areformed in the zigzag pattern in substantially the same manner as theopen regions 27 of the first embodiment shown in FIG. 3A. A stackstructure, including the patterned etch stop layer 44 and the patternedmould layer 45 providing the open regions 47, is referred to as anisolation layer 300.

Referring to FIG. 5B, the photoresist pattern 46 is removed. Aconductive layer 48 for forming the storage nodes is formed over theisolation layer 300 and the open regions 47. The conductive layer 48 mayinclude a metal electrode such as TiN or ruthenium (Ru). The conductivelayer 48 may also include other materials besides TiN and Ru. Theconductive layer 48 may be formed to have a thickness ranging fromapproximately 200 Å to approximately 400 Å using a chemical vapordeposition (CVD) method or an atomic layer deposition (ALD) method.

When forming the conductive layer 48 including TiN using the CVD method,a CVD TiN deposition method is performed using titanium tetrachloride(TiCl₄) as a source and using ammonia (NH₃) as a reaction gas at atemperature ranging from approximately 400° C. to approximately 700° C.When forming the conductive layer 48 including Ru, the ALD method or theCVD method is performed using Ru(EtCp)₂ as a source and using oxygen(O₂) gas as a reaction gas at a temperature ranging from approximately200° C. to approximately 400° C. The conductive layer 48 for use as thestorage nodes may include platinum (Pt) formed by the ALD method oriridium (Ir) formed by the ALD method.

Referring to FIG. 5C, a storage node isolation process is performed. Thestorage node isolation process includes performing a dry etch-backprocess on the conductive layer 48. The storage node isolation processmay include performing a CMP process or a dry etch-back process using aphotoresist layer barrier or an oxide-based layer barrier when theconductive layer 48 includes TiN. Using the photoresist layer barrier orthe oxide-based layer barrier may reduce contamination in the openregions 47 during the storage node isolation process.

The storage node isolation process is performed until top surfaces ofthe patterned mould layer 45 are exposed. Thus, cylinder type storagenodes 48A are formed on the surface of the open regions 47, isolatedfrom each other. In other words, the CMP process or the dry etch-backprocess is performed to remove portions of the conductive layer 48formed outside the open regions 47, thereby forming the cylinder typestorage nodes 48A over bottom surfaces and sidewalls of the open regions47. After the storage node isolation process is performed, the storagenodes 48A are formed on the surface of the open regions 47 of theisolation layer 300. The storage nodes 48A are arranged in a zigzagpattern.

Referring to FIG. 5D, the patterned mould layer 45 is partially etchedto form a remaining mould layer 45A. Thus, upper outer walls 48B of thestorage nodes 48A are exposed. A remaining isolation layer 301 includesthe remaining mould layer 45A and the patterned etch stop layer 44.

The patterned mould layer 45 is selectively etched using an oxideetchant because the patterned mould layer 45 includes an oxide-basedmaterial. For instance, a wet etch may be used. The wet etch may includeperforming a wet dip out process. The wet etch of the patterned mouldlayer 45 may include etching the patterned mould layer 45 to have athickness ranging from approximately 200 nm to approximately 1,000 nmusing a buffered oxide etchant (BOE) or a hydrogen fluoride (HF)solution. For instance, approximately 700 nm to approximately 800 nm ofthe patterned mould layer 45 may be etched.

After the patterned mould layer 45 is partially etched, the remainingisolation layer 301, including the stack structure of the patterned etchstop layer 44 and the remaining mould layer 45A, remains betweenadjacent storage nodes 48A. The upper outer walls 48B of the storagenodes 48A are exposed because portions of the patterned mould layer 45are etched.

Referring to FIG. 5E, a sacrificial layer 49 is formed over the storagenodes 48A and the remaining isolation layer 301. The sacrificial layer49 may include a material which may not be etched or which has asubstantially slow etch rate in a wet etch solution for oxide during asubsequent wet dip out process of the remaining mould layer 45A. Forinstance, the sacrificial layer 49 may include a photoresist layer.

The photoresist layer is not easily etched by wet etch solutions foroxide, such as a BOE or a HF solution. The photoresist layer is easilyremoved through a dry ashing process in an oxidation ambience includingO₂ or ozone (O₃). The photoresist layer is formed to have a certainthickness sufficient to fill small and large spaces defined between thestorage nodes 48A.

Referring to FIG. 5F, a photo-exposure and developing process isperformed on the sacrificial layer 49, thereby forming a sacrificialpattern 49A. The sacrificial pattern 49A remains over the cell region.

The remaining mould layer 45A is etched using the sacrificial pattern49A as an etch barrier. Thus, a mould pattern 45B is formed. The etchingof the remaining mould layer 45A may include performing a dry etchprocess. Portions of the remaining mould layer 45A in the peripheralregions are etched away. Thus, the mould pattern 45B defines spacesaround the cell region into which a wet etch solution may flow. Themould pattern 45B may be formed such that the mould pattern 45B remainsin the cell region after the portions of the remaining mould layer 45Aare etched in the peripheral regions. Alternatively, the mould pattern45B may be formed such that portions of the remaining mould layer 45Aremain over the patterned etch stop layer 44 at a certain thickness inthe peripheral regions. An isolation pattern 311 includes the mouldpattern 45B and the patterned etch stop layer 44.

Referring to FIG. 5G, a wet etch process for oxide is performed. Forinstance, the wet etch process may include performing a wet dip outprocess. The mould pattern 45B including an oxide-based materialremaining in the cell region is removed during the wet dip out process.A wet etch solution flows sideways into the spaces defined around thecell region and removes the mould pattern 45B. Thus, empty spaces 302are formed. The sacrificial pattern 49A is not easily etched during awet dip out process for oxide. Thus, the sacrificial pattern 49Adecreases the likelihood of leaning storage nodes 48A. The wet dip outprocess may use a BOE or a HF solution as an oxide etchant. The wet dipout process is performed for a period of time sufficient to remove themould pattern 45B. According to the third embodiment, the neighboringstorage nodes 48A are supported by the sacrificial pattern 49A duringthe wet dip out process, and thus, the likelihood of leaning storagenodes 48A is reduced during a dry process which is performed after thewet dip out process.

Referring to FIG. 5H, a photoresist ashing process is performed. Thephotoresist ashing process includes a dry ashing process. Thesacrificial pattern 49A is removed using the dry ashing process. Thesacrificial pattern 49A may be removed through a dry ashing using oxygenor ozone. The storage nodes 48A are not damaged because the dry ashingprocess is performed at a low temperature using oxygen.

Although not illustrated, subsequent dielectric layer and upperelectrode formation processes are performed to form a cylinder typecapacitor. The dielectric layer may include tantalum oxide (Ta₂O₅),aluminum oxide (Al₂O₃), titanium oxide (TiO₂), hafnium oxide (HfO₂),zirconium dioxide (ZrO₂), strontium titanate (STO), barium strontiumtitanate (BST), or a combination thereof. The upper electrode mayinclude a TiN layer formed using a CVD method, a TiN layer formed usingan ALD method, a Ru layer formed using a CVD method, a Ru layer formedusing an ALD method, a Pt layer formed using an ALD method, an Ir layerformed using an ALD method, or a combination thereof.

FIGS. 6A to 6G illustrate cross-sectional views of a method forfabricating a cylinder type capacitor according to a fourth embodimentof the present invention.

Referring to FIG. 6A, an insulation layer 52 is formed over asemi-finished substrate 51. The substrate 51 is divided into a cellregion and peripheral regions. Storage node contact holes are formed inthe insulation layer 52, and storage node contact plugs 53 are formed inthe storage node contact holes. Although not illustrated, processes forforming transistors, word lines, and bit lines are generally performedbefore forming the insulation layer 52. The insulation layer 52 mayinclude an undoped silicate glass (USG) layer and may be formed to havea thickness ranging from approximately 1,000 Å to approximately 3,000 Å.A patterned etch stop layer 54 is formed over the insulation layer 52. Apatterned mould layer 55 is formed over the patterned etch stop layer54.

The insulation layer 52 is etched using a storage node contact mask toform the storage node contact holes. A polysilicon layer fills thestorage node contact holes and an etch-back process is performed to formthe storage node contact plugs 53. Although not illustrated, barriermetals may be formed over the storage node contact plugs 53. The barriermetals may include titanium (Ti) or titanium nitride (TiN). An etch stoplayer is formed over the insulation layer 52 and the storage nodecontact plugs 53. The etch stop layer may include a nitride-basedmaterial. For instance, the etch stop layer may include a siliconnitride (Si₃N₄) layer.

A mould layer is formed over the etch stop layer. The mould layer mayinclude an insulation layer. For instance, an oxide-based layer such asa phosphosilicate glass (PSG) layer or a plasma enhanced tetraethylorthosilicate (PETEOS) layer may be formed to have a certain thicknesssufficient to maintain a necessary surface area for a desired dielectriccapacitance. The mould layer may be formed in a double-layer structureincluding oxide-based layers. The double-layer structure may be formedsuch that an upper oxide-based layer has a smaller etch rate in a wetetch solution for oxide than a bottom oxide-based layer. For example,PSG may be formed and PETEOS may then be formed over the PSG in thedouble-layer structure.

A first photoresist layer is formed over the mould layer. Aphoto-exposure and developing process is performed on the firstphotoresist layer to form a first photoresist pattern 56. It isimportant for the first photoresist pattern 56 to form openings in azigzag pattern. The openings are formed in the first photoresist pattern56 where subsequent storage nodes are to be formed. The mould layer isetched using the first photoresist pattern 56 as an etch barrier to formthe patterned mould layer 55 and to form a plurality of open regions 57.The etch stop layer exposed by the open regions 57 is etched to form thepatterned etch stop layer 54 and to expose upper surfaces of the storagenode contact plugs 53.

The open regions 57 are formed to have a trench shape. The open regions57 are also referred to as storage node holes because the subsequentstorage nodes are formed on the surface of the open regions 57. The openregions 57 are formed in a zigzag pattern, mirroring the zigzagarrangement of the first photoresist pattern 56. The open regions 57 areformed in a zigzag pattern in substantially the same manner as the openregions 27 of the first embodiment shown in FIG. 3A. A stack structure,including the patterned etch stop layer 54 and the patterned mould layer55 providing the open regions 57, is referred to as an isolation layer400.

Referring to FIG. 6B, the first photoresist pattern 56 is removed. Aconductive layer 58 for forming the storage nodes is formed over theisolation layer 400 and the open regions 57. The conductive layer 58 mayinclude a metal electrode such as TiN or ruthenium (Ru). The conductivelayer 58 may also include other materials besides TiN and Ru. Theconductive layer 58 may be formed to have a thickness ranging fromapproximately 200 Å to approximately 400 Å using a chemical vapordeposition (CVD) method or an atomic layer deposition (ALD) method.

When forming the conductive layer 58 including TiN using the CVD method,a CVD TiN deposition method is performed using titanium tetrachloride(TiCl₄) as a source and using ammonia (NH₃) as a reaction gas at atemperature ranging from approximately 400° C. to approximately 700° C.When forming the conductive layer 58 including Ru, the ALD method or theCVD method is performed using Ru(EtCp)₂ as a source and using oxygen(O₂) gas as a reaction gas at a temperature ranging from approximately200° C. to approximately 400° C. The conductive layer 58 for forming thestorage nodes may include platinum (Pt) formed by the ALD method oriridium (Ir) formed by the ALD method.

Referring to FIG. 6C, a storage node isolation process is performed. Thestorage node isolation process includes performing a dry etch-backprocess on the conductive layer 58. The storage node isolation processmay include performing a CMP process or a dry etch-back process using aphotoresist layer barrier or an oxide-based layer barrier when theconductive layer 58 includes TiN. Using the photoresist layer barrier orthe oxide-based layer barrier may reduce contamination in the openregions 57 during the storage node isolation process.

The storage node isolation process is performed until top surfaces ofthe patterned mould layer 55 are exposed. Thus, cylinder type storagenodes 58A are formed on the surface of the open regions 57, isolatedfrom each other. In other words, the CMP process or the dry etch-backprocess is performed to remove portions of the conductive layer 58formed outside the open regions 57, thereby forming the cylinder typestorage nodes 58A over bottom surfaces and sidewalls of the open regions57. The storage nodes 58A are formed on the surface of the open regions57 of the isolation layer 400. The storage nodes 58A are formed in azigzag pattern.

Referring to FIG. 6D, a sacrificial layer 59 is formed over the storagenodes 58A and the isolation layer 400. The sacrificial layer 59 mayinclude a material which may not be etched or which has a substantiallyslow etch rate in a wet etch solution for oxide during a subsequent wetdip out process of the patterned mould layer 55. For instance, thesacrificial layer 59 may include an amorphous carbon layer.

The amorphous carbon layer may be formed using a plasma-based depositionmethod, such as a plasma enhanced chemical vapor deposition (PECVD)method or a plasma enhanced atomic layer deposition (PEALD) method. Theamorphous carbon layer is not easily etched by wet etch solutions foroxide, such as a BOE or a HF solution. The amorphous carbon layer iseasily removed by a dry ashing process in an oxidation ambienceincluding O₂ or ozone (O₃). The amorphous carbon layer used as thesacrificial layer 59 is formed at a temperature ranging fromapproximately 200° C. to approximately 500° C.

The sacrificial layer 59 is formed to a certain thickness sufficient tofill a space defined between neighboring storage nodes 58A. Thesacrificial layer 59 may be formed to cover the substrate structurewithout controlling the thickness of the sacrificial layer 59 because adry etch-back process of the sacrificial layer 59 is omitted in thefourth embodiment, unlike the first embodiment.

Referring to FIG. 6E, a second photoresist layer is formed over thesacrificial layer 59. A photo-exposure and developing process isperformed on the second photoresist layer to form a second photoresistpattern 60. The second photoresist pattern 60 covers the cell region butexposes the peripheral regions of the substrate structure.

The sacrificial layer 59 is etched using the second photoresist pattern60 as an etch barrier. Thus, a sacrificial pattern 59A is formed. Thesacrificial pattern 59A remains in the cell region because portions ofthe sacrificial layer 59 in the peripheral regions are etched. Thepatterned mould layer 55 is etched after the sacrificial pattern 59A isformed, thereby forming a mould pattern 55A. The etching of thepatterned mould layer 55 may include performing a dry etch process.Portions of the patterned mould layer 55 in the peripheral regions areetched. Thus, the mould pattern 55A defines spaces around the cellregion into which a wet etch solution may flow. The mould pattern 55Amay be formed such that the mould pattern 55A remains in the cell regionafter the portions of the patterned mould layer 55 are etched in theperipheral regions. Alternatively, the mould pattern 55A may be formedsuch that portions of the patterned mould layer 55 remain over thepatterned etch stop layer 54 at a certain thickness in the peripheralregions. An isolation pattern 401 includes the mould pattern 55A and thepatterned etch stop layer 54.

Referring to FIG. 6F, a wet etch process for oxide is performed. Forinstance, the wet etch process may include performing a wet dip outprocess. The mould pattern 55A including an oxide-based material isremoved during the wet dip out process. A wet etch solution flowssideways into the spaces defined around the cell region and removes themould pattern 55A. Thus, empty spaces 402 are formed between the storagenodes 58A. The sacrificial pattern 59A is not easily etched during a wetdip out process for oxide. Thus, the sacrificial pattern 59A decreasesthe likelihood of leaning storage nodes 58A. The wet dip out process mayuse a BOE or a HF solution as an oxide etchant. The wet dip out processis performed for a period of time sufficient to remove the mould pattern55A. Neighboring storage nodes 58A are supported by the sacrificialpattern 59A during the wet dip out process, and thus, the likelihood ofleaning storage nodes 58A is reduced during a dry process which isperformed after the wet dip out process.

Referring to FIG. 6G, a photoresist ashing process is performed. Thephotoresist ashing process includes a dry ashing process. The secondphotoresist pattern 60 and the sacrificial pattern 59A aresimultaneously removed using the dry ashing process. The sacrificialpattern 59A including amorphous carbon may be removed at substantiallythe same time as the second photoresist pattern 60 because amorphouscarbon can be removed by a dry ashing using oxygen or ozone. The storagenodes 58A are not damaged because the dry ashing process is performed ata low temperature using oxygen.

Although not illustrated, subsequent dielectric layer and upperelectrode formation processes are performed to form a cylinder typecapacitor. The dielectric layer may include tantalum oxide (Ta₂O₅),aluminum oxide (Al₂O₃), titanium oxide (TiO₂), hafnium oxide (HfO₂),zirconium dioxide (ZrO₂), strontium titanate (STO), barium strontiumtitanate (BST), or a combination thereof. The upper electrode mayinclude a TiN layer formed using a CVD method, a TiN layer formed usingan ALD method, a Ru layer formed using a CVD method, a Ru layer formedusing an ALD method, a Pt layer formed using an ALD method, an Ir layerformed using an ALD method, or a combination thereof.

FIGS. 7A to 7G illustrate cross-sectional views of a method forfabricating a cylinder type capacitor according to a fifth embodiment ofthe present invention.

Referring to FIG. 7A, an insulation layer 62 is formed over asemi-finished substrate 61. The substrate 61 is divided into a cellregion and peripheral regions. Storage node contact holes are formed inthe insulation layer 62, and storage node contact plugs 63 are formed inthe storage node contact holes. Although not illustrated, processes forforming transistors, word lines, and bit lines are generally performedbefore forming the insulation layer 62. The insulation layer 62 mayinclude an undoped silicate glass (USG) layer and may be formed to athickness ranging from approximately 1,000 Å to approximately 3,000 Å. Apatterned etch stop layer 64 is formed over the insulation layer 62. Apatterned mould layer 65 is formed over the patterned etch stop layer64.

The insulation layer 62 is etched using a storage node contact mask toform the storage node contact holes. A polysilicon layer fills thestorage node contact holes and an etch-back process is performed to formthe storage node contact plugs 63. Although not illustrated, barriermetals may be formed over the storage node contact plugs 63. The barriermetals may include titanium (Ti) or titanium nitride (TiN). An etch stoplayer is formed over the insulation layer 62 and the storage nodecontact plugs 63. The etch stop layer may include a nitride-basedmaterial. For instance, the etch stop layer may include a siliconnitride (Si₃N₄) layer.

A mould layer is formed over the etch stop layer. The mould layer mayinclude an insulation layer. For instance, an oxide-based layer such asa phosphosilicate glass (PSG) layer or a plasma enhanced tetraethylorthosilicate (PETEOS) layer may be formed to have a certain thicknesssufficient to maintain a necessary surface area for a desired dielectriccapacitance. The mould layer may be formed in a double-layer structureincluding oxide-based layers. The double-layer structure may be formedsuch that an upper oxide-based layer has a smaller etch rate in a wetetch solution for oxide than a bottom oxide-based layer. For example,PSG may be formed and PETEOS may be then formed over the PSG in thedouble-layer structure.

A photoresist layer is formed over the mould layer. A photo-exposure anddeveloping process is performed on the photoresist layer to form aphotoresist pattern 66. It is important for the photoresist pattern 66to define openings in a zigzag pattern. The openings are defined in thephotoresist pattern 66 where subsequent storage nodes are to be formed.The mould layer is etched using the photoresist pattern 66 as an etchbarrier to form the patterned mould layer 65 and to form a plurality ofopen regions 47. The etch stop layer exposed by the open regions 67 isetched to form the patterned etch stop layer 64 and to expose uppersurfaces of the storage node contact plugs 63.

The open regions 67 are formed to have a trench shape. The open regions67 are also referred to as storage node holes because the subsequentstorage nodes are formed on the surface of the open regions 67. The openregions 67 are formed in a zigzag pattern, mirroring the zigzagarrangement of the photoresist pattern 66. The open regions 67 areformed in a zigzag pattern in substantially the same manner as the openregions 27 of the first embodiment shown in FIG. 3A. A stack structure,including the patterned etch stop layer 64 and the patterned mould layer65 providing the open regions 67, is referred to as an isolation layer500.

Referring to FIG. 7B, the photoresist pattern 66 is removed. Aconductive layer 68 for forming the storage nodes is formed over theisolation layer 500 and the open regions 67. The conductive layer 68 mayinclude a metal electrode such as TiN or ruthenium (Ru). The conductivelayer 68 may also include other materials besides TiN and Ru. Theconductive layer 68 may be formed to a thickness ranging fromapproximately 200 Å to approximately 400 Å using a chemical vapordeposition (CVD) method or an atomic layer deposition (ALD) method.

When forming the conductive layer 68 including TiN using the CVD method,a CVD TiN deposition method is performed using titanium tetrachloride(TiCl₄) as a source and using ammonia (NH₃) as a reaction gas at atemperature ranging from approximately 400° C. to approximately 700° C.When forming the conductive layer 68 including Ru, the ALD method or theCVD method is performed using Ru(EtCp)₂ as a source and using oxygen(O₂) gas as a reaction gas at a temperature ranging from approximately200° C. to approximately 400° C. The conductive layer 68 for forming thestorage nodes may include platinum (Pt) formed by the ALD method oriridium (Ir) formed by the ALD method.

Referring to FIG. 7C, a storage node isolation process is performed. Thestorage node isolation process includes performing a dry etch-backprocess on the conductive layer 68. The storage node isolation processmay include performing a CMP process or a dry etch-back process using aphotoresist layer barrier or an oxide-based layer barrier when theconductive layer 68 includes TiN. Using the photoresist layer barrier orthe oxide-based layer barrier may reduce contamination in the openregions 67 during the storage node isolation process.

The storage node isolation process is performed until top surfaces ofthe patterned mould layer 65 are exposed. Thus, cylinder type storagenodes 68A are formed on the surface of the open regions 67, isolatedfrom each other. In other words, the CMP process or the dry etch-backprocess is performed to remove portions of the conductive layer 68formed outside the open regions 67, thereby forming the cylinder typestorage nodes 68A over bottom surfaces and sidewalls of the open regions67. The storage nodes 68A are formed on the surface of the open regions67 of the isolation layer 500. The storage nodes 68A are formed in azigzag pattern.

Referring to FIG. 7D, a sacrificial layer 69 is formed over the storagenodes 68A and the isolation layer 500. The sacrificial layer 69 mayinclude a material which may not be etched or which has a substantiallyslow etch rate in a wet etch solution for oxide during a subsequent wetdip out process of the patterned mould layer 65. For instance, thesacrificial layer 69 may include a photoresist layer.

The photoresist layer is not easily etched by wet etch solutions foroxide, such as a BOE or a HF solution. The photoresist layer is easilyremoved through a dry ashing process in an oxidation ambience includingO₂ or ozone (O₃). The photoresist layer is formed to a certain thicknesssufficient to fill a space defined between the storage nodes 68A. Thesacrificial layer 69 may be formed to cover the substrate structurewithout controlling the thickness of the sacrificial layer 69 because adry etch-back process of the sacrificial layer 69 is omitted in thefifth embodiment, unlike the first embodiment.

Referring to FIG. 7E, a photo-exposure and developing process isperformed on the sacrificial layer 69, thereby forming a sacrificialpattern 69A. The sacrificial pattern 69A remains over the cell regionand exposes the peripheral regions.

The patterned mould layer 65 is etched using the sacrificial pattern 69Aas an etch barrier. Thus, a mould pattern 65A is formed. The etching ofthe patterned mould layer 65 may include performing a dry etch process.Portions of the patterned mould layer 65 in the peripheral regions areetched. Thus, the mould pattern 65A defines spaces around the cellregion into which a wet etch solution may flow. The mould pattern 65Amay be formed such that the mould pattern 65A remains in the cell regionafter the portions of the patterned mould layer 65 are etched in theperipheral regions. Alternatively, the mould pattern 65A may be formedsuch that portions of the patterned mould layer 65 remain over thepatterned etch stop layer 64 at a certain thickness in the peripheralregions. Isolation pattern 501 includes the mould pattern 65A and thepatterned etch stop layer 64.

Referring to FIG. 7F, a wet etch process for oxide is performed. Forinstance, the wet etch process may include performing a wet dip outprocess. The mould pattern 65A including an oxide-based materialremaining in the cell region is removed during the wet dip out process.A wet etch solution flows sideways into the spaces defined around thecell region and removes the mould pattern 65A. Thus, empty spaces 602are formed. The sacrificial pattern 69A is not easily etched during awet dip out process for oxide. Thus, the sacrificial pattern 69Adecreases the likelihood of leaning storage nodes 68A. The wet dip outprocess may use a BOE or a HF solution as an oxide etchant. The wet dipout process is performed for a period of time sufficient to remove themould pattern 65A. The neighboring storage nodes 68A are supported bythe sacrificial pattern 69A during the wet dip out process, and thus,the likelihood of leaning storage nodes 68A is reduced during a dryprocess which is performed after the wet dip out process.

Referring to FIG. 7G, a photoresist ashing process is performed. Thephotoresist ashing process includes a dry ashing process. Thesacrificial pattern 69A is removed using the dry ashing process. Thesacrificial pattern 69A may be removed through a dry ashing using oxygenor ozone. The storage nodes 68A are not damaged because the dry ashingprocess is performed at a low temperature using oxygen.

Although not illustrated, subsequent dielectric layer and upperelectrode formation processes are performed to form a cylinder typecapacitor. The dielectric layer may include tantalum oxide (Ta₂O₅),aluminum oxide (Al₂O₃), titanium oxide (TiO₂), hafnium oxide (HfO₂),zirconium dioxide (ZrO₂), strontium titanate (STO), barium strontiumtitanate (BST), or a combination thereof. The upper electrode mayinclude a TiN layer formed using a CVD method, a TiN layer formed usingan ALD method, a Ru layer formed using a CVD method, a Ru layer formedusing an ALD method, a Pt layer formed using an ALD method, an Ir layerformed using an ALD method, or a combination thereof.

According to the second through fifth embodiments of the presentinvention, the sacrificial layer formed in the large space between thestorage nodes may not have to be removed by the dry etch-back process.The sacrificial layer may decrease the occurrence of leaning storagenodes, regardless of the step coverage characteristic of the sacrificiallayer in accordance with the deposition methods such as a PECVD methodor a PEALD method. In other words, the process shown in the firstembodiment may be varied according to the step coverage characteristicof the sacrificial layer, in which the dry etch-back process isperformed on the sacrificial layer to form the sidewall shapedsacrificial layer around the upper outer walls of the storage nodes.

While the present invention has been described with respect to thespecific embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims.

1. A method for fabricating a capacitor, comprising: forming anisolation layer over a substrate, the isolation layer forming aplurality of open regions; forming storage nodes on surfaces of the openregions; etching an upper portion of the isolation layer to expose upperouter walls of the storage nodes; forming a sacrificial layer over theisolation layer, wherein the sacrificial layer is formed in a connectedring structure that encloses the upper outer walls of the storage nodes;with the connected ring structure supporting the storage nodes, removingthe isolation layer; and removing the connected ring structure.
 2. Themethod of claim 1, wherein the open regions are formed in a zigzagpattern.
 3. The method of claim 1, wherein forming the sacrificial layercomprises: forming the sacrificial layer over the upper outer walls ofthe storage nodes; and etching the sacrificial layer into the connectedring structure.
 4. The method of claim 3, wherein forming thesacrificial layer further comprises forming the sacrificial layer to acertain thickness to fill a space defined between neighboring storagenodes spaced apart less than a predetermined distance and to not fill aspace defined between neighboring storage nodes spaced apart more thanthe predetermined distance.
 5. The method of claim 4, wherein thesacrificial layer is formed using a plasma-based deposition method. 6.The method of claim 5, wherein the sacrificial layer is formed using oneof: a plasma enhanced chemical vapor deposition (PECVD) method and aplasma enhanced atomic layer deposition (PEALD) method.
 7. The method ofclaim 4, wherein etching the sacrificial layer comprises performing adry etch-back process.
 8. The method of claim 1, wherein the sacrificiallayer and the isolation layer each comprise a material having an etchrate different from each other.
 9. The method of claim 8, wherein theisolation layer comprises an oxide-based layer and the sacrificial layercomprises an amorphous carbon layer.
 10. The method of claim 1, whereinetching the isolation layer and removing the isolation layer compriseperforming a wet etch process.
 11. The method of claim 10, whereinperforming the wet etch process comprises using one of: a buffered oxideetchant (BOE) and a hydrogen fluoride (HF) solution.
 12. The method ofclaim 10, wherein etching the isolation layer comprises removingapproximately 200 nm to approximately 1,000 nm of the isolation layer.13. The method of claim 12, wherein etching the isolation layercomprises removing approximately 700 nm to approximately 800 nm of theisolation layer.
 14. The method of claim 1, wherein removing thesacrificial layer comprises performing a dry ashing process.
 15. Themethod of claim 14, wherein performing the dry ashing process comprisesusing one of: oxygen and ozone.
 16. The method of claim 1, wherein thestorage nodes comprise one selected from a group consisting of: titaniumnitride (TiN), ruthenium (Ru), platinum (Pt), and iridium (Ir).
 17. Amethod for fabricating a capacitor, comprising: forming an isolationlayer over a cell region and a peripheral region of a substrate, theisolation layer forming a plurality of open regions in the cell region;forming storage nodes on surfaces of the open regions; etching an upperportion of the isolation layer to expose upper outer walls of thestorage nodes; forming a sacrificial pattern over the isolation layer,wherein the sacrificial pattern is formed in a connected ring structurethat encloses the upper outer walls of the storage nodes; etching theisolation layer in the peripheral region to expose side portions of theresultant structure obtained after forming the sacrificial pattern; withthe connected ring structure supporting the storage nodes, removing theisolation layer in the cell region; and removing the connected ringstructure.
 18. The method of claim 17, wherein the sacrificial patternand the isolation layer each comprise a material having an etch ratedifferent from each other.
 19. The method of claim 18, wherein theisolation layer comprises an oxide-based layer and the sacrificialpattern comprises an amorphous carbon layer.
 20. The method of claim 18,wherein the isolation layer comprises an oxide-based layer and thesacrificial pattern comprises a photoresist layer.
 21. The method ofclaim 17, wherein etching the isolation layer to expose the sideportions of the resultant structure comprises performing a dry etchprocess.
 22. The method of claim 21, wherein removing the isolationlayer comprises performing a wet dip out process and then performing adry process.
 23. The method of claim 22, wherein the wet dip out processcomprises using one of: a buffered oxide etchant (BOE) and a hydrogenfluoride (HF) solution.
 24. The method of claim 17, wherein removing thesacrificial pattern comprises performing a dry ashing process.
 25. Themethod of claim 24, wherein performing the dry ashing process comprisesusing one of: oxygen and ozone.
 26. The method of claim 17, wherein theopen regions are formed in a zigzag pattern.
 27. The method of claim 17,wherein etching the upper portion of the isolation layer comprisesremoving approximately 200 nm to approximately 1,000 nm of the isolationlayer.
 28. The method of claim 27, wherein etching the upper portion ofthe isolation layer comprises removing approximately 700 nm toapproximately 800 nm of the isolation layer.
 29. The method of claim 17,wherein forming the sacrificial pattern comprises: forming a sacrificiallayer over the upper outer walls of the storage nodes; and etching thesacrificial layer into the connected ring pattern.
 30. The method ofclaim 29, wherein forming the sacrificial pattern further comprisesforming the sacrificial pattern to a certain thickness to fill a spacedefined between neighboring storage nodes spaced apart less than apredetermined distance and to not fill a space defined betweenneighboring storage nodes spaced apart more than the predetermineddistance.